Biology subjects

Sartorio, M. G.

Publications and source records attributed to Sartorio, M. G..

2 recordsLinked to original sources

bioRxiv2021

Coping with oxidative stress in extreme environments: the distinctive roles played by Acinetobacter sp. Ver3 superoxide dismutases

Acinetobacter sp. Ver3 is a polyextremophilic strain characterized by a high tolerance to radiation and pro-oxidants. The Ver3 genome comprises the sodB and sodC genes encoding an iron (AV3SodB) and a copper/zinc superoxide dismutase (AV3SodC), respectively; however, the specific role(s) of these genes has remained elusive. We show that the expression of sodB remained unaltered in different oxidative stress conditions whereas sodC was up-regulated in the presence of blue light. Besides, we studied the changes in the in vitro activity of each SOD enzyme in response to diverse agents and solved the crystal structure of AV3SodB at 1.34 [A], one of the highest resolutions achieved for a SOD. Cell fractionation studies interestingly revealed that AV3SodB is located in the cytosol whereas AV3SodC is also found in the periplasm. Consistently, a bioinformatic analysis of the genomes of 53 Acinetobacter species pointed out the presence of at least one SOD type in each compartment, suggesting that these enzymes are separately required to cope with oxidative stress. Surprisingly, AV3SodC was found in an active state also in outer membrane vesicles, probably exerting a protective role. Overall, our multidisciplinary approach highlights the relevance of SOD enzymes when Acinetobacter spp. are confronted with oxidizing agents.

microbiology↗

bioRxiv2021

Modern Acinetobacter baumannii clinical isolates replicate inside spacious vacuoles and egress from macrophages

Multidrug-resistant Acinetobacter baumannii infections are increasing at alarming rates. Therefore, novel antibiotic-sparing treatments to combat these A. baumannii infections are urgently needed. The development of these interventions would benefit from a better understanding of this bacteriums pathobiology, which remains poorly understood. A. baumannii is regarded as an extracellular opportunistic pathogen. However, research on Acinetobacter has largely focused on common lab strains, such as ATCC 19606, that have been isolated several decades ago. These strains exhibit reduced virulence when compared to recently isolated clinical strains. In this work, we demonstrate that, unlike ATCC 19606, several modern A. baumannii clinical isolates, including the recent clinical urinary isolate UPAB1, persist and replicate inside macrophages within spacious vacuoles. We show that intracellular replication of UPAB1 is dependent on a functional type I secretion system (T1SS) and pAB5, a large conjugative plasmid that controls the expression of several chromosomally-encoded genes. Finally, we show that UPAB1 escapes from the infected macrophages by a lytic process. To our knowledge, this is the first report of intracellular growth and replication of A. baumannii. We suggest that intracellular replication within macrophages may contribute to evasion of the immune response, dissemination, and antibiotic tolerance of A. baumannii.

microbiology↗